The correct answer is: Fill the box with electrolyte solution.
Why: Before loading the samples into the wells for gel electrophoresis, the gel must be submerged in a proper running buffer (electrolyte solution). This buffer provides the necessary ions to allow the electric current to pass through the gel and facilitates the movement of the charged DNA or proteins in the sample. Once the gel is properly filled with running buffer, then Tysha can load her samples into the wells.